Only the content area is freezing at all pages

-- url of the page with the problem -- : localhost
-- HikaShop version -- : 2.2.1
-- Joomla version -- : 2.5
-- PHP version -- : 5.4.10
-- Browser(s) name and version -- : chrome 28.0.1500.95
-- Error-message(debug-mod must be tuned on) -- : Error_message none

I am developing e-commerce with Hikashop.
Only the content area is freezing. I cannot click and input at form.
The menu is working.
But the second level of the menu is hidden behind the content area.

I tried z-index:999 for <ul>, <li> and z-index:-999 for content area at css.

2 issues, freezing and menu, might be different independent problem or not.

Please help me.

Hi nicolas,
Thank you for your reply.
I uploaded the website from a local test server to hosting company server temporarily.
idilanew.idiapparel.com/

Thanks,

Thank you for your reply.

I could solve them.
As you said, one of the cause was that some unused css z-index remained.
The second cause of css was overflow:hidden; for dropdown menu of #header.

Thanks,